1. Field of Invention
This invention relates to systems and methods for automatically detecting the width of a document using a backing image.
2. Description of Related Art
To provide an image processing apparatus with image data to process, the image data is often captured from original images using an image capture device, such as a scanner. The image capture device converts the various light and dark areas of the original image to a set of digital signals, and provides these digital signals to the image processing apparatus to be processed. These processed digital signals can then be used to operate an image output terminal, such as, for example, a printing apparatus.
In conventional image capture devices, the user must manually determine the document size and input the width to the image capture device before the image of the document is captured. The document must be centered to avoid clipping the output image.
This invention provides systems and method for automatically detecting a document""s width and position when the document is being initially staged for image capture.
This invention separately provides systems and methods that provide automatic detection of the width and position of a document, where the detection is substantially insensitive to dust and dirt as well as electrical noise.
In various exemplary embodiments of the systems and method of this invention, it is not necessary for a user to manually determine the document size or center the document. In various exemplary embodiments of the systems and method of this invention, image capture is performed with an illuminating device and a photosensor. During image capture, the area surrounding the document has a different density from the body of the document, which permits the document""s edges to be identified.
In various exemplary embodiments of the methods and systems of this invention, image processing routines are performed upon the image of the document and not upon the image data representing the backing, i.e., the area captured by the digital image capture device which is not the document or the desired image to be captured.
In various exemplary embodiments of the systems and method of this invention, when a document is staged for image capture, the image capture device collects several scanlines of the backing without the document and several scanlines of the lead edge of the document with the backing. The collected backing image is then subtracted from the collected lead edge image, and the resulting image is readjusted.
In various exemplary embodiments of the systems and method of this invention, variations in the backing areas of the lead edge image are removed and edge detection failures and/or errors are reduced or eliminated.
These and other features and advantages of this invention are described in or are apparent from the following detailed description of various exemplary embodiments.